The major objective of the project is to investigate the development of mastery motivation in the first year of life. In a previous study, (Z01 HD00008-04) three aspects of mastery were distinguished: persistence in problem solving, in practicing emerging sensorimotor skills, and in obtaining sensory feedback from the physical environment. The interrelationships among these three components of mastery motivation are being explored. The origins of mastery in parent-child transactions and their continuity over time are being studied. The sample includes 69 infants from middle income families. Several methods are being employed--a series of twelve tasks devised to measure mastery motivation; mother-infant observation and father-infant interaction at home; Bayley Scales of Infant Development; and several self-report measures of parent-infant interaction. Analyses will focus on continuity in mastery behavior between 6 and 12 months and on the relationship between the development of mastery and parent-infant interaction.